Superregular grammars do not provide additional explanatory power but
allow for a compact analysis of animal song

A pervasive belief with regard to the differences between human language and
animal vocal sequences (song) is that they belong to different classes of
computational complexity, with animal song belonging to regular languages,
whereas human language is superregular. This argument, however, lacks empirical
evidence since superregular analyses of animal song are understudied. The goal
of this paper is to perform a superregular analysis of animal song, using data
from gibbons as a case study, and demonstrate that a superregular analysis can
be effectively used with non-human data. A key finding is that a superregular
analysis does not increase explanatory power but rather provides for compact
analysis. For instance, fewer grammatical rules are necessary once
superregularity is allowed. This pattern is analogous to a previous
computational analysis of human language, and accordingly, the null hypothesis,
that human language and animal song are governed by the same type of
grammatical systems, cannot be rejected.